There is an ever increasing need for communications with satellites, including reception of satellite broadcasts such as television and data and transmission to satellites in vehicles such as trains, cars, SUVs etc. that are fitted with one or more receivers and/or transmitters, not only when the vehicle is stationary (such as during parking) but also when it is moving.
The known antenna systems for use for mobile Direct Broadcast Satellite (DBS) reception can be generally divided into several main types. One type utilizes a reflector or lens antenna with fully mechanical steering. Another type uses phased array antennas comprised of a plurality of radiating elements. The mechanically steerable reflector antenna has a relatively large volume and height, which, when enclosed in the necessary protective radome for mobile use, is too large and undesirable for some mobile applications, especially for ground vehicles. For use with in-motion applications, the antenna housing as a whole should be constrained to a relatively low height profile when mounted on a vehicle.
The array type comprises at least three sub-groups depending on the antenna beam steering means—fully electronic (such as the one disclosed in U.S. Pat. No. 5,886,671 Riemer et al.); fully mechanical; and combined electronic and mechanical steering. The present invention relates to the last two sub-groups.
Other patents related to antenna systems include U.S. Pat. Nos. 6,975,885, 6,067,453, 5,963,862, 5,963,862, 6,977,621, 6,950,061, 5,835,057, 5,835,057, 6,977,621, 6,653,981, 6,204,823 and U.S. Patent Publication: 20020167449.
Phased array antennas are built from a certain number of radiating elements displaced in planar or conformal lattice arrangement with suitable shape and size. They typically take the form of conformal or flat panels that utilize the available space more efficiently than reflector solutions and therefore can provide a lower height profile. In certain cases the mentioned panel arrangements can be divided into two or more smaller panels in order to reduce further the height, thereby rendering such arrangements more suitable for vehicles. Such an antenna for DBS receiving is described in A MOBILE 12 GHZ DBS TELEVISION RECEIVING SYSTEM, authored by Yasuhiro Ito and Shigeru Yamazaki in “IEEE Transactions on Broadcasting,” Vol. 35, No. 1, March 1989 (hereinafter “the Ito et al. publication”).
There is thus a need in the art to provide a mobile antenna system with low profile and better radiation pattern keeping relatively low cost, suitable for mounting on moving platforms where the size is an issue as is the case in RVs trains, SUVs, bus, boats etc.